What are the functions of zinc oxide?

We have all renovated our homes, and I wonder if you have noticed that the paints or varnishes used for decoration often contain a common chemical substance - zinc oxide. Its main function is to give paint or coating a certain gloss. Some doctors say it can also be used to make medicines. Is this true? What other functions does zinc oxide have? In what fields can it be used?

Zinc Oxide

Zinc oxide is an oxide of zinc. Insoluble in water, soluble in acids and strong alkalis. Zinc oxide is a commonly used chemical additive, widely used in the production of plastics, silicate products, synthetic rubber, lubricants, paints and coatings, ointments, adhesives, foods, batteries, flame retardants and other products. Zinc oxide has a large band gap and exciton binding energy, high transparency, and excellent room-temperature luminescence properties. It is used in liquid crystal displays, thin-film transistors, light-emitting diodes and other products in the semiconductor field. In addition, microparticle zinc oxide as a nanomaterial has also begun to play a role in related fields.

Physical properties

Appearance and properties: White powder or hexagonal crystals. Odorless, tasteless, non-gritty. It turns yellow when heated, turns white again after cooling, and sublimates when heated to 1800℃. The hiding power is half of titanium dioxide and zinc sulfide. The tinting power is twice that of alkaline lead carbonate.

Solubility: Soluble in acid, concentrated alkali hydroxide, ammonia and ammonium salt solution; insoluble in water and ethanol.

Chemical properties

Zinc oxide is a famous white pigment, commonly known as zinc white. Its advantage is that it does not turn black when encountering H2S gas because ZnS is also white. When heated, ZnO gradually changes from white and light yellow to lemon yellow, and the yellow color disappears when cooled. Based on this property, it can be added to paint or thermometers to make color-changing paints or color-changing thermometers. Because ZnO has astringency and certain bactericidal ability, it is often prepared into ointments for use in medicine. ZnO can also be used as a catalyst.

Chemical reaction formula:

Reaction with NaOH: ZnO + 2NaOH + H2O = Na2[Zn(OH)4]